The instant invention relates to an open-end rotor spinning device as well as to an aerostatic axial bearing for the spinning rotor.
A rotor spinning device of this type is known from DE 39 42 612 A1. In such a device the shaft is mounted in a nip of supporting disks and is driven by means off a drive, e.g. a tangential belt. An axial thrust upon the rotor shaft which is supported by an aerostatic axial bearing is produced via the supporting disks. This aerostatic bearing is located at the free end of the rotor shaft away from the rotor and is installed on the machine housing or on the seat of the bearing of the supporting disks. In an effort to continually increase the rotational speed of the rotor to the point where it is now around 120,000 RPMs and more, the shafts of the open-end spinning rotors were continually shortened so that the distance between the bearing points of the rotor shaft on the supporting disks has also become shorter and shorter in axial direction. In addition to the bearing points of the rotor on the supporting disks, the tangential belt or a driving disk driving the rotor also constitutes an additional fastening of the rotor because the shaft is thereby pushed into the nips of the supporting disk pairs.
With open-end spinning devices in which the shaft of the spinning rotor is axially supported upon a ball, such as is shown in DE 36 22 523 A1 for example, it is a known method to design the seals of the axial bearing so that when the supporting disk diameter changes, the rotor shaft is able to move against a sliding surface in order to save the seal of the axial bearing. In this design the overhang of the shaft, i.e. the length of the shaft from the supporting disk pair toward the axial bearing to the free end of the rotor shaft measures approximately 20 mm.
In the rotor spinning device of the type according to DE 39 42 612 A1, the overhang of the free end of the rotor shaft is very short in the actual model. Thus, very high rotational speeds can be attained with the rotor since the short overhang of the free end of the rotor shaft has a very favorable effect upon the oscillation attitude of the rotor shaft. The short overhang can be achieved in the rotor bearing of that type in that the aerostatic axial bearing only influences the surface of the free end of the rotor shaft. In axial bearings which are operated by means of an oil-lubricated ball, expensive measures are required to seal off the oil vapors which emerge from such a bearing and soil the rotor spinning device. The open-end spinning device of this type has also the disadvantage that the space availability at the free end of the shaft is extremely restricted. This has as a consequence that a radial guidance of the shaft end could not be used in the past. Such a radial support is especially favorable when the rotor is greatly out of balance because of said rotor being soiled and runs unsteadily. It is possible here that the aerostatic bearing is under greater stress from the radially oscillating free end of the rotor shaft, so that damage to the bearing is possible in spite of good emergency running characteristics.